Human performance oxygen sensor and headset

ABSTRACT

A system for detecting unsafe equipment operation conditions using physiological sensors includes a plurality of wearable physiological sensors, each physiological sensor of the plurality of wearable physiological sensors configured to detect at least a physiological parameter of an operator of an item of equipment, and a processor in communication with the at least a physiological sensor and designed and configured to determine an equipment operation parametric model, wherein the equipment operation parametric rule relates physiological parameter sets to equipment operation requirements, detect using the equipment operation parametric model and the plurality of physiological parameters, a violation of an equipment operation requirement, and generate a violation response action in response to detecting the violation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Non-provisional application Ser. No. 16/859,483 filed on Apr. 27, 2020 and entitled “HUMAN PERFORMANCE OXYGEN SENSOR,” the entirety of which is incorporated herein by reference. Non-provisional application Ser. No. 16/859,483, in turn, is a continuation-in-part of and claims the benefit of priority of U.S. Nonprovisional patent application Ser. No. 15/492,612, filed on Apr. 20, 2017, and titled “HUMAN PERFORMANCE OXYGEN SENSOR,” the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to physiological sensing devices, and in particular to human performance oxygen sensors, headsets and related systems and methods.

BACKGROUND

Blood oxygen saturation can determine a plurality of physical characteristics and ailments, including determining whether an individual is on the verge of losing consciousness. Typically, sensors measuring oxygenation are placed on the fingers or foreheads of patients and do not include a means of analyzing the data and alerting the user or a third party of whether an issue has been determined.

SUMMARY OF THE DISCLOSURE

In an aspect, an exemplary system for measuring oxygenation signals includes an outer shell, a seal coupled to the outer shell, a blood oxygen sensor configured to be in contact with a user, be located behind an ear of the user, and measure an oxygenation signal of the user, and a processor configured to receive the oxygenation signal from the blood oxygen sensor and compare the oxygenation signal from the blood oxygenation sensor with known human performance data.

In another aspect, an exemplary method for measuring oxygenation signals uses a system comprising an outer shell, a seal coupled to the outer shell, a blood oxygen sensor, and a processor. The exemplary method includes contacting a user, using the blood oxygen sensor, locating the blood oxygen sensor behind an ear of the user, measuring, using the blood oxygen sensor, an oxygenation signal of the user, receiving, using the processor, the oxygenation signal from the blood oxygen sensor, and comparing, using the processor, the oxygenation signal from the blood oxygenation sensor with known human performance data.

These and other aspects and features of non-limiting embodiments of the present invention will become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 shows a perspective view of a device according to an embodiment disclosed herein;

FIG. 2 shows a front view of a device according to an embodiment disclosed herein;

FIG. 3 shows a side view of a device according to an embodiment disclosed herein;

FIG. 4 shows a perspective view of a device according to an embodiment disclosed herein;

FIG. 5 shows a front sectional view of a device according to an embodiment disclosed herein;

FIG. 6 is a schematic illustration of an exemplary embodiment of a near-infrared spectroscopy sensor;

FIG. 7 is a schematic diagram of some aspects of user cranial anatomy in an embodiment;

FIG. 8 illustrates a block diagram of an embodiment of a system incorporating a device according to an embodiment;

FIG. 9 illustrates a flow diagram of an embodiment of a method of detecting unsafe equipment operation conditions using physiological sensors; and

FIG. 10 is a block diagram of a computing system that can be used to implement any one or more of the methodologies disclosed herein and any one or more portions thereof. The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.

DETAILED DESCRIPTION

In an embodiment, systems, devices and methods disclosed herein detect physiological parameters such as blood oxygen level, blood pressure, neurological oscillations, and heart rate of a user who is operating an item of equipment such as an aircraft through nonintrusive means. Sensors mounted in optimal locations on the head or neck of the user may detect physiological parameters accurately, minimizing interference in activities the user engages in while obtaining a clearer signal than otherwise would be possible. Embodiments of the disclosed device may provide users such as pilots, firemen, and divers who are operating under extreme circumstances with an early warning regarding potential crises such as loss of consciousness, affording the user a few precious extra seconds to avert disaster. Alarms may be provided to the user via bone-conducting transducers or by integration into displays the user is operating, increasing the likelihood that the user will notice the warning in time. Embodiments of devices, systems, and methods herein may enable training for pilots or other persons to function within physiological limitations imposed by their environment, such as hypoxemia imposed by altitude, high G forces and the like; training may further enable users to learn how to avoid total impairment, and to function under partial impairment.

Referring now to FIGS. 1-5 , an exemplary embodiment of a perspective view (FIG. 1 ), a side view (FIG. 2 ), a front view (FIG. 3 ), a perspective view (FIG. 4 ), and a front sectional view (FIG. 5 ) of a device for measuring physiological parameters 100 is illustrated. Referring now to FIG. 1 , device for measuring physiological parameters 100 includes a housing 104. Housing 104 may be mounted to an exterior body surface of a user; exterior body surface may include, without limitation, skin, nails such as fingernails or toenails, hair, an interior surface of an orifice such as the mouth, nose, or ears, or the like. A locus on exterior body surface for mounting of housing 104 and/or other components of device may be selected for particular purposes as described in further detail below. Exterior body surface and/or locus may include an exterior body surface of user's head, face, or neck. Housing 104 may be constructed of any material or combination of materials, including without limitation metals, polymer materials such as plastics, wood, fiberglass, carbon fiber, or the like. Housing 104 may include an outer shell 108. Outer shell 108 may, for instance, protect elements of device 100 from damage, and maintain them in a correct position on a user's body as described in further detail below. Housing 104 and/or outer shell 108 may be shaped, formed, or configured to be inserted between a helmet worn on a head of the user and the exterior body surface; housing 104 and/or outer shell 108 may be shaped to fit between the helmet and the exterior body surface. As a non-limiting example, exterior body surface may be a surface, such as a surface of the head, face, or neck of user, which is wholly or partially covered by helmet, as described for example in further detail below. As a further non-limiting example, housing 104 may be formed to have a similar or identical shape to a standard-issue “ear cup” incorporated in an aviation helmet, so that housing 104 can replace ear cup after ear cup has been removed; in an embodiment, device 100 may incorporate one or more elements of ear-cup, including sound-dampening properties, one or more speakers or other elements typically used to emit audio signals in headsets or headphones, or the like. As a non-limiting example, device 100, housing 104, and/or shell may form a form-fit replacement for standard earcups found in military flight helmets. Shell may be rigid, where “rigid” is understood as having properties of an exterior casing typically used in an earcup, over-ear headphone, hearing protection ear covering, or the like; materials used for such a shell may include, without limitation, rigid plastics such as polycarbonate shell plastics typically used in helmets and hardhats, metals such as steel, and the like. Persons skilled in the art, upon reading the entirety of this disclosure, will understand “rigid” in this context as signifying sufficient resistance to shear forces, deformations, and impacts to protect electronic components as generally required for devices of this nature.

Still viewing FIGS. 1-5 , housing 104 may include a seal 112 that rests against exterior body surface when housing 104 is mounted thereon. Seal 112 may be pliable; seal 112 may be constructed of elastomeric, elastic, or flexible materials including without limitation flexible, elastomeric, or elastic rubber, plastic, silicone including medical grade silicone, gel, and the like. Pliable seal 112 may include any combination of materials demonstrating flexible, elastomeric, or elastic properties, including without limitation foams covered with flexible membranes or sheets of polymer, leather, or textile material. As a non-limiting example, pliable seal 112 may include any suitable pliable material for a skin-contacting seal portion of an earcup or other device configured for placement over a user's ear, including without limitation any pliable material or combination of materials suitable for use on headphones, headsets, earbuds, or the like. In an embodiment, pliable seal 112 advantageously aids in maintaining housing 104 and/or other components of device 100 against exterior body surface; for instance, where exterior body surface has elastomeric properties and may be expected to flex, stretch, or otherwise alter its shape or position to during operation, pliable seal 112 may also stretch, flex, or otherwise alter its shape similarly under similar conditions, which may have the effect of maintaining seal 112 and/or one or more components of device 100 as described in greater detail below, in consistent contact with the exterior body surface. Seal 112 may be attached to housing 104 by any suitable means, including without limitation adhesion, fastening by stitching, stapling, or other penetrative means, snapping together or otherwise engaging interlocking parts, or the like. Seal 112 may be removably attached to housing 104, where removable attachment signifies attachment according to a process that permits repeated attachment and detachment without noticeable damage to housing 104 and/or seal 112, and without noticeable impairment of an ability to reattach again by the same process. As a non-limiting example, pliable seal 112 may be placed on an ear cup (for instance shown for exemplary purposes in FIG. 3 ) of the housing 104; pliable seal maybe formed of materials and/or in a shape suitable for use as an ear seal in an ear cup of a helmet, an over-ear headphone or hearing protection device, or the like. Persons skilled in the art, upon reviewing this disclosure in its entirety, will be aware of forms and material properties suitable for use as seal 112, including without limitation a degree and/or standard of pliability required and/or useful to function as a seal 112 in this context.

With continued reference to FIGS. 1-5 , housing 104 may include, be incorporated in, or be attached to an element containing additional components to device 100. For instance, in an embodiment, housing 104 may include, be incorporated in, or be attached to a headset; headset may include, without limitation, an aviation headset, such as headsets as manufactured by the David Clark company of Worcester Mass., or similar apparatuses. In some embodiments, housing 104 is headset; that is, device 100 may be manufactured by incorporating one or more components into the headset, using the headset as a housing 104. As a further non-limiting example, housing 104 may include a mask; a mask as used herein may include any device or element of clothing that is worn on a face of user during operation, occluding at least a part of the face. Masks may include, without limitation, safety googles, gas masks, dust masks, self-contained breathing apparatuses (SCBA), self-contained underwater breathing apparatuses (SCUBA), and/or other devices worn on and at least partially occluding the face for safety, functional, or aesthetic purposes. Housing 104 may be mask; that is, device 100 may be manufactured by incorporating one or more elements or components of device 100 in or on mask, using mask as housing 104. Housing 104 may include, be incorporated in, or be attached to an element of headgear, defined as any element worn on and partially occluding a head or cranium of user. Headgear may wholly or partially occlude user's face and thus also include a mask; headgear may include, for instance, a fully enclosed diving helmet, space helmet or helmet incorporated in a space suit, or the like. Headgear may include a headband, such as without limitation a headband of a headset, which may be an aviation headset. Headgear may include a hat. Headgear may include a helmet, including a motorcycle helmet, a helmet used in automobile racing, any helmet used in any military process or operation, a construction “hardhat,” a bicycle helmet, or the like. In an embodiment, housing 104 is shaped to conform to a particular portion of user anatomy when placed on exterior body surface; when placed to so conform, housing 104 may position at least a sensor and/or user-signaling device 128 in a locus chosen as described in further detail below. For instance, where housing 104 is incorporated in a helmet, mask, earcup or headset, housing 104 may be positioned at a particular portion of user's head when helmet, mask, earcup or headset is worn, which may in turn position at least a sensor and/or user-signaling device 128 at a particular locus on user's head or neck.

Continuing to refer to FIGS. 1-5 , device 100 includes at least a physiological sensor 116. At least a physiological sensor 116 is configured to detect at least a physiological parameter and transmit an electrical signal as a result of the detection; transmission of an electrical signal, as used herein, includes any detectable alternation of an electrical parameter of an electrical circuit incorporating at least a physiological sensor 116. For instance, at least a physiological sensor 116 may increase or reduce the impedance and/or resistance of a circuit to which at least a physiological sensor 116 is connected. At least a physiological sensor 116 may alter a voltage or current level, frequency, waveform, amplitude, or other characteristic at a locus in circuit. Transmission of an electrical signal may include modulation or alteration of power circulating in circuit; for instance transmission may include closing a circuit, transmitting a voltage pulse through circuit, or the like. Transmission may include driving a non-electric signaling apparatus such as a device for transmitting a signal using magnetic or electric fields, electromagnetic radiation, optical or infrared signals, or the like.

Still referring to FIGS. 1-5 , at least a physiological parameter, as used herein, includes any datum that may be captured by a sensor, and describing a physiological state of user. At least a physiological parameter may include at least a circulatory and/or hematological parameter, which may include any detectable parameter describing the state of blood vessels such as arteries, veins, or capillaries, any datum describing the rate, volume, pressure, pulse rate, or other state of flow of blood or other fluid through such blood vessels, chemical state of such blood or other fluid, or any other parameter relative to health or current physiological state of user as it pertains to the cardiovascular system. As a non-limiting example, at least a circulatory parameter may include a blood oxygenation level of user's blood. At least a circulatory parameter may include a pulse rate. At least a circulatory parameter may include a blood pressure level. At least a circulatory parameter may include heart rate variability and rhythm. At least a circulatory parameter may include a plethysmograph describing user blood-flow; in an embodiment, plethysmograph may describe a reflectance of red or near-infrared light from blood. One circulatory parameter may be used to determine, detect, or generate another circulatory parameter; for instance, a plethysmograph may be used to determine pulse and/or blood oxygen level (for instance by detecting plethysmograph amplitude), pulse rate (for instance by detecting plethysmograph frequency), heart rate variability and rhythm (for instance by tracking pulse rate and other factors over time), and blood pressure, among other things. At least a physiological sensor may be configured to detect at least a hematological parameter of at least a branch of a carotid artery; at least a physiological parameter may be positioned to capture the at least a hematological parameter by placement on a location of housing that causes at least a physiological sensor to be placed in close proximity to the at least a branch; for instance, where housing is configured to be mounted to a certain location on a user's cranium, and in a certain orientation, such as when housing forms all or part of a helmet, headset, mask, element of headgear, or the like, at least a physiological sensor may include a sensor so positioned on the housing or an extension thereof that it will contact or be proximate to a locus on the user's skin under which the at least a branch runs. As a non-limiting example, where device 100 forms an earcup or earphone, at least a physiological sensor 116 may include a sensor disposed on or embedded in a portion of the earcup and/or earphone contacting a user's skin over a major branch of the external carotid artery that runs near or past the user's ear.

In an embodiment, and still viewing FIGS. 1-5 , detection of hematological parameters of at least a branch of a carotid artery may enable device 100 to determine hematological parameters of a user's central nervous system with greater accuracy than is typically found in devices configured to measure hematological parameters. For instance, a blood oxygen sensor placed on a finger or other extremity may detect low blood oxygen levels in situations in which the central nervous system is still receiving adequate oxygen, because a body's parasympathetic response to decreasing oxygen levels may include processes whereby blood perfusion to the appendages is constricted in order to sustain higher oxygen levels to the brain; in contrast, by directly monitoring the oxygenation of a major branch of the external carotid artery, the measurement of oxygenation to the central nervous system may be more likely to achieve a more accurate indication of oxygen saturation than a peripheral monitor. Use of the carotid artery in this way may further result in a more rapid detection of a genuine onset of hypoxemia; as a result, a person such as a pilot that is using device 100 may be able to function longer under conditions tending to induce hypoxemia, knowing that an accurate detection of symptoms may be performed rapidly and accurately enough to warn the user. This advantage may both aid in and be augmented by use with training processes as set forth in further detail below.

With continued reference to FIGS. 1-5 , at least a physiological sensor 116 may include a hydration sensor; hydration sensor may determine a degree to which a user has an adequate amount of hydration, where hydration is defined as the amount of water and/or concentration of water versus solutes such as electrolytes in water, in a person's body. Hydration sensor may use one or more elements of physiological data, such as sweat content and/or hematological parameters detected without limitation using plethysmography, to determine a degree of hydration of a user; degree of hydration may be associated with an ability to perform under various circumstances. For instance, a person with adequate hydration may be better able to resist the effects of hypoxemia in high-altitude and/or high-G for longer or under more severe circumstances, either because the person's body is better able to respond to causes of hypoxemia and delay onset, or because the person is better able to cope with diminished blood oxygen; this may be true of other conditions and/or physiological states detected using at least a physiological sensor 116, and may be detected using heuristics or relationships derived, without limitation, using machine learning and/or data analysis as set forth in further detail below.

Still referring to FIGS. 1-5 , at least a physiological sensor 116 may include a volatile organic compound (VOC) sensor. VOC sensor may sense VOCs, including ketones such as acetone; a user may emit ketones in greater quantities when undergoing some forms of physiological stress, including without limitation hypoglycemia resulting from fasting or overwork, which sometimes results in a metabolic condition known as ketosis. As a result, detections of higher quantities of ketones may indicate a high degree of exhaustion or low degree of available energy; this may be associated with a lessened ability to cope with other physiological conditions and/or parameters that may be detected by or using at least a physiological sensor 116, such as hypoxemia, and/or environmental stressors such as high altitude or G-forces. Such associations may be detected or derived using data analysis and/or machine learning as described in further detail below.

With continued reference to FIGS. 1-5 , at least a physiological parameter may include neural oscillations generated by user neurons, including without limitation neural oscillations detected in the user's cranial region, sometimes referred to as “brainwaves.” Neural oscillations include electrical or magnetic oscillations generated by neurological activity, generally of a plurality of neurons, including superficial cranial neurons, thalamic pacemaker cells, or the like. Neural oscillations may include alpha waves or Berger's waves, characterized by frequencies on the order of 7.5-12.5 Hertz, beta waves, characterized by frequencies on the order of 13-30 Hertz, delta waves, having frequencies ranging from 1-4 Hertz, theta waves, having frequencies ranging from 4-8 Hertz, low gamma waves having frequencies from 30-70 Hertz, and high gamma waves, which have frequencies from 70-150 Hertz. Neurological oscillations may be associated with degrees of wakefulness, consciousness, or other neurological states of user, for instance as described in further detail below. At least a sensor may detect body temperature of at least a portion of user's body, using any suitable method or component for temperature sensing.

Still referring to FIGS. 1-5 , at least a physiological sensor 116 may include an optical sensor, which detects light emitted, reflected, or passing through human tissue. Optical sensor may include a near-infrared spectroscopy sensor (NIRS). A NIRS, as used herein, is a sensor that detects signals in the near-infrared electromagnetic spectrum region, having wavelengths between 780 nanometers and 2,500 nanometers. FIG. 6 illustrates an exemplary embodiment of a NIRS 600 against an exterior body surface, which may include skin. NIRS 600 may include a light source 604, which may include one or more light-emitting diodes (LEDs) or similar element. Light source 604 may, as a non-limiting example, convert electric energy into near-infrared electromagnetic signals. Light source 604 may include one or more lasers. NIRS 600 may include one or more detectors 608 configured to detect light in the near-infrared spectrum. Although the wavelengths described herein are infrared and near-infrared, light source 604 may alternatively or additionally emit light in one or more other wavelengths, including without limitation blue, green, ultraviolet, or other light, which may be used to sense additional physiological parameters. In an embodiment, light source may include one or more multi-wavelength light emitters, such as one or more multi-wavelength LEDs, permitting detection of blood-gas toxicology. Additional gases or other blood parameters so detected may include, without limitation CO2 saturation levels, state of hemoglobin as opposed to blood oxygen saturation generally. One or more detectors 608 may include, without limitation, charge-coupled devices (CCDs) biased for photon detection, indium gallium arsenide (InGaAs) photodetectors, lead sulfide (PbS) photodetectors, or the like. NIRS 600 may further include one or more intermediary optical elements (not shown), which may include dispersive elements such as prisms or diffraction gratings, or the like. In an embodiment, NIRS 600 may be used to detect one or more circulatory parameters, which may include any detectable parameter further comprises at least a circulatory parameter. At least a physiological sensor 116 may include at least two sensors mounted on opposite sides of user's cranium.

Referring again to FIGS. 1-5 , at least a physiological sensor 116 may include a neural activity sensor. A neural activity sensor, as used herein, includes any sensor disposed to detect electrical or magnetic phenomena generated by neurons, including cranial neurons such as those located in the brain or brainstem. Neural activity sensor may include an electroencephalographic sensor. Neural activity sensor may include a magnetoencephalographic sensor. In an embodiment, neural activity sensor may be configured to detect neural oscillations. At least a sensor may include an eye-tracking sensor, such as one or more cameras for tracking the eyes of user. Eye-tracking sensor may include, as a non-limiting example, one or more electromyographic (EMG) sensors, which may detect electrical activity of eye muscles; electrical activity may indicate activation of one or more eye muscles to move the eye and used by a circuit such as an alert circuit as described below to determine a movement of user's eyeball, and thus its current location of focus.

Continuing to refer to FIGS. 1-5 , device 100 may communicate with one or more physiological sensors that are not a part of device 100; one or more physiological sensors may include any sensor suitable for use as at least a physiological sensor 116 and/or any other physiological sensor. Communication with physiological sensors that are not part of device may be accomplished by any means for wired or wireless communication between devices and/or components as described herein. Device may detect and/or measure at least a physiological parameter using any suitable combination of at least a physiological sensor and/or physiological sensors that are not a part of device 100. Device 100 may combine two or more physiological parameters to detect a physiological condition and/or physiological alarm condition. For instance, and without limitation, where device 100 is configured to detect hypoxic incapacitation and/or one or more degrees of hypoxemia as described in further detail below, device 100 may perform such determination using a combination of heart rate and blood oxygen saturation, as detected by one or more sensor as described above.

Still viewing FIGS. 1-5 , at least a physiological sensor 116 may be attached to housing 104; attachment to housing 104 may include mounting on an exterior surface of housing 104, incorporation within housing 104, electrical connection to another element within housing 104, or the like. Alternatively or additionally, at least a physiological sensor 116 may include a sensor that is not attached to housing 104 or is indirectly attached via wiring, wireless connections, or the like. As a non-limiting example, at least a physiological sensor 116 and/or one or more components thereof may be coupled to the pliable seal 112. In an embodiment, at least a physiological sensor 116 may be contacting exterior body surface; this may include direct contact with the exterior body surface, or indirect contact for instance through a portion of seal 112 or other components of device 100. In an embodiment, at least a physiological sensor 116 may contact a locus on the exterior body surface where substantially no muscle is located between the exterior body surface and an underlying bone structure, meaning muscle is not located between the exterior body surface and an underlying bone structure and/or any muscle tissue located there is unnoticeable to a user as a muscle and/or incapable of appreciably flexing or changing its width in response to neural signals; such a locus may include, as a non-limiting example, locations on the upper cranium, forehead, nose, behind the ear, at the end of an elbow, on a kneecap, at the coccyx, or the like. Location at a locus where muscle is not located between exterior body surface and underlying bone structure may decrease reading interference and/or inaccuracies created by movement and flexing of muscular tissue. At least a physiological sensor 116 may contact a locus having little or no hair on top of skin. At least a physiological sensor 116 may contact a locus near to a blood vessel, such as a locus where a large artery such as the carotid artery or a branch thereof, or a large vein such as the jugular vein, runs near to skin or bone at the location; in an embodiment, such a position may permit at least a physiological sensor 116 to detect circulatory parameters as described above.

Referring now to FIG. 7 , a schematic diagram of anatomy of a portion of a user cranium 700 is illustrated for exemplary purposes. At least a physiological sensor 116 may, for instance, be placed at or near to a locus adjacent to a branch 704 of a carotid artery, which may be a branch of an exterior carotid artery. At least a physiological sensor 116 may be placed at a location 708 where substantially no muscle is found between a user's skin and bone; such a location may be found, for instance, near to the user's neck behind the ear. In an embodiment, at least a physiological sensor may be placed in a locus that is both adjacent to a branch 704 of a carotid artery and has substantially no muscle between skin and bone. In an embodiment, measurement of at least a physiological parameter, including without limitation pulse oxygenation and/or pulse rate as described in further detail below, on a particular portion of the cranium may eliminate interfering factors such as sweat and movement artifact; measurement above the neck may further eliminate measurement issues experienced at the extremities (finger, wrist) due to temperature variation, movement and blood pooling under G. Where multiple physiological sensors of at least a physiological sensor 116 are used, at least two sensors may be placed at two locations on a user's cranium; for instance, two sensors, one on each side of the cranium, may provide validation of consistent data, and assures a high capture rate of data in flight. Two sensors may be so placed, as noted elsewhere in this disclosure, by form and/or configuration of housing 104; for instance, housing 104 may include two earcups or other over-ear devices as described above.

As a non-limiting example of placement of at least a physiological sensor 116, and as illustrated for exemplary purposes in FIGS. 1-5 , at least a physiological sensor 116 may include a sensor mounted on an edge of an earcup, and so positioned that placement of earcup over user's ear places sensor in contact with user's head just behind the ear at a local skeletal eminence, with substantially no muscle tissue between skin and bone and a branch of the carotid artery nearby for detection of circulatory parameters. Similarly, where housing 104 includes a mask as described above, a sensor of at least a physiological sensor 116 may be disposed within mask at a location that, when mask is worn, places sensor against a forehead of user.

Still viewing FIGS. 1-5 , where at least a physiological sensor 116 includes a neural activity sensor, at least a physiological sensor 116 may include one or more sensors placed in locations suitable for detection of neural activity, such as on upper surfaces of a cranium of user, or similar locations as suitable for EEG or MEG detection and measurement.

With continued reference to FIGS. 1-5 , device 100 may include a processor 120 in communication with the at least a physiological sensor. As used herein, a device, component, or circuit is “in communication” where the device, component, or circuit is able to receive data from and/or transmit data to another device, component, or circuit. In an embodiment, devices are placed in communication by electrically coupling at least an output of one device, component, or circuit to at least an input of another device, component, or circuit. Devices may further be placed in communication by creating an optical, inductive, or other coupling between two or more devices. Devices in communication may be placed in near field communication with one another. Two or more devices may be in communication where the two or more devices are configured to send and/or receive signals to or from each other. Placement of devices in communication may include direct or indirect connection and/or transmission of data; for instance, two or more devices may be connected or otherwise in communication by way of an intermediate circuit. Placement of devices in communication with each other may be performed via a bus or other facility for intercommunication between elements of a computing device as described in further detail in this disclosure. Placement of devices in communication with each other may include fabrication together on a shared integrated circuit and/or wafer; for instance, and without limitation, two or more communicatively coupled devices may be combined in a single monolithic unit or module.

With continued reference to FIGS. 1-5 , processor 120 may be constructed according to any suitable process or combination of processes for constructing an electrical circuit; for instance, and without limitation, processor 120 may include a printed circuit board. Processor 120 may include a battery or other power supply; where processor 120 is integrated in one or more other systems as described in further detail below, processor 120 may draw electrical power from one or more circuit elements and/or power supplies of such systems. Processor 120 may include a memory; memory may include any memory as described below in reference to FIG. 11 . Processor 120 may include one or more processors as described in further detail below in reference to FIG. 11 , including without limitation a microcontroller or low-power microprocessor. In an embodiment, memory may be used to store one or more signals received from at least a physiological sensor 116.

Still referring to FIGS. 1-5 , processor 120 may be in communication with at least an environmental sensor 124; at least an environmental sensor 124 may be any sensor configured to detect at least an environmental parameter, defined herein as a parameter describing non-physiological data concerning user or surroundings of user, such as acceleration, carbon monoxide, or the like. At least an environmental sensor 124 may include at least a motion sensor, including without limitation one or more accelerometers, gyroscopes, magnetometers, or the like; at least a motion sensor may include an inertial measurement unit (IMU). At least an environmental sensor 124 may include at least a temperature sensor. At least an environmental sensor 124 may include at least an air quality sensor, such as without limitation a carbon monoxide sensor, or other sensor of any gas or particulate matter in air. At least an environmental sensor may include an atmospheric oxygen sensor, an oxygen flow meter, and/or a mask oxygen/CO₂ sensor. At least an environmental sensor 124 may include at least a barometric sensor. At least an environmental sensor 124 may include a pressure sensor, for instance to detect air or water pressure external to user. Processor 120 may be attached to housing 104, for instance by incorporation within housing 104; as a non-limiting example and as shown in FIG. 5 , the processor 120 may be housed along an inner wall of the housing 104. Processor 120 may be attached to an exterior of housing 104. According to an embodiment, a covering may be placed over housing 104, fully enclosing the processor 120 within the housing 104; the enclosure may include a plastic, a metal, a mesh-type material, and/or any other suitable material. Processor 120 may be in another location not attached to or incorporated in housing 104. Processor 120 may be incorporated into and/or connected to one or more additional elements including any elements incorporating or connected to user signaling devices as described in further detail below. As an alternative to storage of one or more parameter values such as physiological parameters or environmental parameters in memory, alert circuit may transmit the data to one or more remote storage mediums through one or more wired and/or wireless means.

Still viewing FIGS. 1-5 , processor 120 may be configured to receive at least a signal from the at least a physiological sensor 116, generate an alarm as a function of the at least a signal, and to transmit the alarm to a user-signaling device 128 in communication with the processor 120. Processor 120 may periodically sample data from at least a sensor; in a non-limiting example, data may be sampled 75 times per second; alternatively, or additionally, sampling of any sample and/or parameter may be event driven, such as a sensor that activates upon a threshold of a sensed parameter being crossed, which may trigger an interrupt of processor 120, or the like. In an embodiment, alarm is generated upon detection of any signal at all from at least a physiological sensor 116; for instance, at least a physiological sensor 116 may be configured only to signal processor 120 upon detection of a problematic or otherwise crucial situation. Alternatively or additionally, processor 120 is further configured to detect a physiological alarm condition and generate the alarm as a function of the physiological alarm condition. In an embodiment, a physiological alarm condition includes any physiological condition of user that may endanger user or impair user's ability to perform an important task; as a non-limiting example, if user is flying an aircraft and user's physiological condition is such that user is unable to concentrate, respond rapidly to changing conditions, see or otherwise sense flight controls or conditions, or otherwise successfully operate the aircraft within some desired tolerance of ideal operation, a physiological alarm condition may exist, owing to the possibility of inefficient or dangerous flight that may result. Similarly, if user's physiological condition indicates user is experiencing or about to experience physical harm, is losing or is about to lose consciousness, or the like, a physiological alarm condition may exist.

Still referring to FIGS. 1-5 , processor 120 may be configured to perform any embodiment of any method and/or method step as described in this disclosure. For instance, and without limitation, processor 120 may be designed and configured to detect at least a flight condition having a causative association with hypoxemia, measure, using at least a physiological sensor, at least a physiological parameter associated with hypoxemia, and determine, by the processor 120, and based on the at least a physiological parameter, a degree of pilot hypoxemia.

In an embodiment, and still viewing FIGS. 1-5 , detection of a physiological alarm condition may include comparison of at least a physiological parameter to a threshold level. For instance, and without limitation, detection of the physiological alarm condition further comprises determination that the at least a physiological parameter is falling below a threshold level; as an example, blood oxygen levels below a certain cutoff indicate an imminent loss of consciousness, as may blood pressure below a certain threshold. Similarly detection of a physiological alarm condition may include detection of alpha wave activity falling below a certain point, which may indicate entry into early stages of sleep or a hypnogogic state, and/or entry into unconsciousness. Comparison to threshold to detect physiological alarm condition may include comparison of at least a physical parameter to a value stored in memory, which may be a digitally stored value; alternatively or additionally comparison may be performed by analog circuitry, for instance by comparing a voltage level representing at least a physical parameter to a reference voltage representing the threshold, by means of a comparator or the like. Threshold may represent or be represented by a baseline value. Detection of a physiological alarm condition may include comparison to two thresholds; for instance, detection that incapacitation and/or loss of consciousness due to hypoxemia is imminent may include detection that a user's heart rate has exceeded one threshold for heart rate and simultaneous or temporally proximal detection that blood oxygen saturation has fallen below a second threshold. Threshold or thresholds used for such comparison to detect a physiological alarm condition may include universal and/or default thresholds. For instance, device 100 may be set, prior to use with a particular individual, with thresholds corresponding to a typical user's response to physiological conditions. For instance, device 100 may initially store a threshold in memory of device 100 of 70% blood oxygen saturation, as indicating that a typical user is likely incapacitated by hypoxemia when blood oxygen saturation of that user, including blood oxygen saturation in a cranial vessel such as a branch of a carotid artery, has fallen below 70%; however, data gathered regarding a particular user may indicate that the particular user is only likely to be incapacitated at 65% blood oxygen saturation and/or that the particular user is likely to be incapacitated at 75% blood oxygen saturation, and threshold may be modified in memory accordingly.

Still referring to FIGS. 1-5 , in an embodiment, a single physiological parameter and/or combination of physiological parameters may be associated with a plurality of thresholds indicating a plurality of degrees of physiological conditions, such as degrees of incapacitation. As a non-limiting example, a plurality of thresholds may be stored regarding blood oxygen saturation, such as without limitation a first threshold indicating a possible saturation problem, a second indicating a degree of blood oxygen saturation consistent with some degree of performance degradation on the part of the user, and a third threshold indicating that incapacitation is likely. By way of illustration, and without limitation, default or factory-set thresholds may include a first threshold triggered upon a user crossing into 80-90% blood oxygen saturation, indicating “saturation possible problem,” a second threshold upon the user crossing into 70-80% saturation, indicating “Performance degraded,” and a third threshold upon the user crossing into <70% saturation indicating “incapacitation likely,” while 90-100% saturation may indicate a normal amount of blood oxygen saturation. Generally, multiple thresholds may be set just above physiologically-relevant levels corresponding to onset of symptoms, cognitive impairment, and total incapacitation for a very-accurate, user-specific warning tone. User-specific thresholds at any tier or degree of incapacitation may be set and/or adjusted according to an iterative process, where users define thresholds, and/or the system finds user thresholds based on, as a non-limiting example, user-specific training and/or sortie data. Determination that of an alarm state such as alarm states associated with one or more thresholds as described above may alternatively or additionally be performed without a threshold comparison, for instance by identifying a correlation of two or more sensor data determined, for instance using machine learning as described below, to be associated with entry into such one or more alarm states; as a non-limiting example, detection of imminent incapacitation and/or unconsciousness due to hypoxemia may be accomplished by detecting a simultaneous or temporally correlated increase in heart rate and decrease in blood oxygen saturation. Combinations or associations of sensor data may further involve measuring several human performance metrics including SPO2, Pulse Rate, and full plethysmograph as well as environmental sensor data such as flight conditions for full characterization and correlation of human performance in flight, for instance as described in further detail below.

Still referring to FIGS. 1-5 , detection of physiological alarm condition may include comparing at least a physiological parameter to at least a baseline value and detecting the physiological alarm condition as a function of the comparison. At least a baseline value may include a number or set of numbers representing normal or optimal function of user, a number or set of numbers representing abnormal or suboptimal function of user, and/or a number or set of numbers indicating one or more physiological parameters demonstrating a physiological alarm condition. At least a baseline value may include at least a threshold as described above. In an embodiment, at least a baseline value may include a typical user value for one or more physiological parameters. For example, and without limitation, at least a baseline value may include a blood oxygen level, blood pressure level, pulse rate, or other circulatory parameter, or range thereof, consistent with normal or alert function in a typical user; at least a baseline value may alternatively or additionally include one or more such values or ranges consistent with loss of consciousness or impending loss of consciousness in a typical user. Similarly, at least a baseline value may include a range of neural oscillations typically associated in users with wakeful or alert states of consciousness, and/or a range of neural oscillations typically associated with sleeping or near-sleeping states, loss of consciousness or the like. Processor 120 may receive a typical user value and using the typical user value as the baseline value; for instance, processor 120 may have typical user value entered into memory of processor 120 by a user or may receive typical user value over a network or from another device. At least a baseline value may be maintained in any suitable data structure, including a table, database, linked list, hash table, or the like.

Continuing to refer to FIGS. 1-5 , typical user value may include a user value matched to one or more demographic facts about user. For instance, a pulse rate associated with loss of consciousness in women may not be associated with loss of consciousness in men, or vice-versa; where user is a woman, the former pulse rate may be used as a baseline value for pulse rate. Baseline value may similarly be selected using a typical value for persons matching user's age, sex, height, weight, degree of physical fitness, physical test scores, ethnicity, diet, or any other suitable parameter. Typical user baseline value may be generated by averaging or otherwise aggregating baseline values calculated per user as described below; for instance, where each user has baseline values established by collection of physiological parameters using devices such as device 100, such values may be collected, sorted according to one or more demographic facts, and aggregated to produce a typical user baseline value to apply to user. Still referring to FIGS. 1-5 , baseline value may be created by collection and analysis of at least a physiological parameter; collection and/or analysis may be performed by processor 120 and/or another device in communication with processor 120. For instance, receiving a baseline value may include collecting a plurality of samples of the at least a physiological parameter and calculating the baseline value as a function of the plurality of samples. Device 100 may continuously or periodically read or sample signals from at least a physiological sensor 116, recording the results; such results may be timestamped or otherwise co-associated, such that patterns concerning physiological parameters may be preserved, detected, and/or analyzed. For example and without limitation, user pulse rate and/or blood pressure may vary in a consistent manner with blood oxygen level; user blood pressure and/or pulse rate may further vary in a consistent manner with brain wave activity. Additional information from other sensors may similarly collected to form baseline value; for instance, where user is operating a machine, such as an aircraft, data concerning operation, such as flight control data, may be collected and associated with at least a physiological parameter. As a non-limiting example, user's reaction time when operating an aircraft may be measurably slower when user's blood pressure is below a certain amount, while showing no particular change for variations in blood pressure above that amount. Additional information may further be provided by user and/or another person evaluation user behavior and/or performance. For example, during test flights or other operation of an aircraft where user and/or aircraft may be observed, user, a supervisor, or another observer may record information such as the user's performance, the user's feelings or apparent state of health, the performance of the aircraft, and the like. Some factors that may be relatively objectively monitored regarding the overall state of health experience by the user may include how many times the user has to use “anti-G” breathing exercises, or similar activities. In an embodiment, data is received from user and/or observers via numerical ratings, or selections of buttons or other entry devices that map to numerical ratings. Alternatively or additionally, entries may be formed using one or more text entries; text entries may be mapped to numerical ratings or the like using, as a non-limiting example, natural language analysis, textual vector analysis, or the like. Plurality of physiological parameters and/or user entries and other entries may be collected over time, during, for instance a series of routine activities by user.

Continuing to refer to FIGS. 1-5 , baseline value may be generated by collection of data from at least an environmental sensor 124. For instance, each set of one or more physiological parameters taken at a particular moment, or over a particular period of time, may be linked in memory to one or more environmental parameters, including without limitation motion-sensor data, air quality data, and the like. This may be used by device 100, as a non-limiting example, to collect relationships between environmental parameters and physiological parameters, such as a relationship between localized or systemic blood pressure, G-forces, and state of consciousness of a user in an aircraft, or a relationship between quality of neural oscillations and external water pressure in a diver. This in turn may be used to produce additional baseline information as described in further detail below. As further examples, relationships determined to achieve baseline values may include comparisons of heart rate, heart rate increase and heart rate recovery are easily compared to scientifically derived norms established in academia and professional athletics. Relationships may include correlation of blood oxygen saturation, heart rate and heart rate variability. These metrics may be useful for objectively determining deliberate risk levels associated with human performance, for instance using population data and/or machine learning as described in further detail below. In an embodiment, a baseline study of each individual performance against known conditions, such as in the Restricted Oxygen Breathing Device, may be performed prior to use of device 10; a purpose of the baseline evaluation may be to assess how each individual responds to specific conditions. Such a response may be used to both validate the data to draw usable conclusions, as well as to calibrate the alarm system to provide meaningful data while reducing the incidence of false alarms, for instance by setting and/or adjusting default threshold levels as described above.

With continued reference to FIGS. 1-5 , plurality of physiological parameters, plurality of environmental parameters, and/or user-entered data may be aggregated, either independently or jointly. For instance, device 100 may calculate an average level, for one or more parameters of at least a physiological parameter, associated with normal or optimal function, health, or performance of user; a standard deviation from the average may also be calculated. This may be used, e.g., to generate an alarm indicating that, for instance, a given physiological parameter has recently shifted more than a threshold amount from its average value. Threshold amount may be determined based on amounts by which a typical user may deviate from average amount before experiencing discomfort, loss of function, or loss of consciousness. Threshold amount may be set as some multiple of standard deviations, as calculated from sensed physiological parameters; for instance, two or more standard deviations from an average value for a given detected physiological parameter may trigger an alarm.

Alternatively or additionally, and still referring to FIGS. 1-5 , aggregation may include aggregation of relationships between two or more parameters. For instance, and without limitation, aggregation may calculate a relationship between a first physiological parameter of the at least a physiological parameter and a second physiological parameter of the at least a physiological parameter; this relationship may be calculated, as a non-limiting example, by selecting a first parameter as a parameter associated with a desired state for the user and a second parameter known or suspected to have an effect on the first parameter. For example, first parameter may be blood oxygen level, and second parameter may be blood pressure, such as localized blood pressure in a cranial region; a reduction in cranial blood pressure may be determined to be related to a reduction in cranial blood oxygen level, which in turn may be related to loss of consciousness or other loss of function in user or in a typical user. As another example, aggregation may calculate a relationship between a physiological parameter of the at least a physiological parameter and an environmental parameter. For example, blood oxygen level may be inversely related to an amount of acceleration or G force a user is experiencing in an aircraft; this relationship may be directly calculated from those two values, or indirectly calculated by associating the amount of acceleration or G force with a degree of decrease in cranial blood pressure, which may then be related to blood oxygen levels. Aggregation may calculate a relationship between at least a physiological parameter and user-entered data; for instance, people observing user may note losses of performance or apparent function at times associated with a certain degree of decrease in blood oxygen level or some other physiological parameter. The relationships may be between combinations of parameters: for instance, loss of function may be associated with an increase in G forces coupled with a decrease in pulse rate, or a decrease in blood oxygen coupled with a decrease in alpha waves, or the like.

Still referring to FIGS. 1-5 , relationships between two or more of any of physiological parameters, environmental parameters, and/or user-entered parameters may be determined by one or more machine-learning algorithms. A “machine learning process” or “machine-learning algorithm,” as used in this disclosure, is a process that automatedly uses a body of data known as “training data” and/or a “training set” to generate an algorithm that will be performed by a computing device/module to produce outputs given data provided as inputs; this is in contrast to a non-machine learning software program where the commands to be executed are determined in advance by a user and written in a programming language. Machine learning may function by measuring a difference between predicted answers or outputs and goal answers or outputs representing ideal or “real-world” outcomes the other processes are intended to approximate. Predicted answers or outputs may be produced by an initial or intermediate version of the process to be generated, which process may be modified as a result of the difference between predicted answers or outputs and goal answers or outputs. Initial processes to be improved may be created by a programmer or user or may be generated according to a given machine-learning algorithm using data initially available. Inputs and goal outputs may be provided in two data sets from which the machine learning algorithm may derive the above-described calculations; for instance a first set of inputs and corresponding goal outputs may be provided and used to create a mathematical relationship between inputs and outputs that forms a basis of an initial or intermediate process, and which may be tested against further provided inputs and goal outputs. Data sets representing inputs and corresponding goal outputs may be continuously updated with additional data; machine-learning process may continue to learn from additional data produced when machine learning process analyzes outputs of “live” processes produced by machine-learning processes. As a non-limiting example, an unsupervised machine-learning algorithm may be performed on training sets describing co-occurrences of any or all parameters in time; unsupervised machine-learning algorithm may calculate relationships between parameters and such co-occurrences. This may produce an ability to predict a likely change in a physiological parameter as a function of detected changes in one or more environmental parameters; thus, a physiological alarm condition may be detected when a set of alarm parameters are trending in a way associated with decreases in blood oxygen, causing a blood oxygen warning to be generated before any decrease in blood oxygen is detected. With continued reference to FIGS. 1-5 , a supervised machine learning algorithm may be used to determine an association between one or more detected parameters and one or more physiological alarm conditions or other outcomes or situations of interest or concern. For instance, a supervised machine-learning algorithm may be used to determine a relationship between one or more sets of parameters, such as physiological parameters, environmental parameters, and/or user-entered information, and one or more physiological alarm conditions. To illustrate, a mathematical relationship between a set of physiological and environmental parameters as described above and a loss of consciousness, or near loss of consciousness, by user, may be detected by a supervised machine-learning process; such a process may include a linear regression process, for instance, where a linear combination of parameters may is assumed to be associated with a physiological alarm condition, and collected parameter data and associated data describing the physiological alarm condition are evaluated to determine the linear combination by minimizing an error function relating outcomes of the linear combination and the real-world data. Polynomial regression may alternatively assume one or more polynomial functions of parameters and perform a similar minimization process. Alternatively or additionally neural net-based algorithms or the like may be used to determine the relationship.

Still viewing FIGS. 1-5 , each of the above processes for aggregation and/or machine learning may further be compared to test data, such as data gathered concerning user physiological parameters, performance, and/or function, in one or more testing facilities or protocols; such facilities or protocols may include, for instance, centrifuge testing of a user's response to acceleration and/or G forces, tests administered to monitor one or more physiological parameters and/or user function or performance under various adverse conditions such as sleep deprivation, boredom, and the like, or any other tests administered to determine the effect of various conditions on user. Such test data may be collected using device 100, or alternatively may be collected using one or more other devices, medical facilities, and the like. Any aggregation and/or machine learning as described above may be applied to test data, independently or combined with other data gathered as described above; for instance, in an embodiment, test data may be combined with typical user data to achieve a first baseline, which may be compared to further data gathered as described above to modify the baseline and generate a second baseline using any suitable aggregation or machine-learning methodology. Collected and/or aggregated data may be provided to users, such as supervisors or commanders, who may use collected and/or aggregated data to monitor state of health of individual users or groups of users. In an embodiment, device 100 may store data collected during a period of activity, such as a flight where device 100 is used with a pilot and may provide such data to another device upon completion of the period of activity. For instance, device 100 may download stored data into a file for storage and tracking; data file may be analyzed using an indigenously designed application to determine areas of further study, allowing a detailed look at portions of ground operations or flight in which physio-logical responses can be compared to known conditions. File and/or collected data may be transferred to a remote computing device via network, wired, or wireless communication; for instance, and without limitation, device 100 may be connected to or placed in communication with remote device after each flight or other period of activity. Where device 100 is incorporated in an element of headgear such as a helmet, headset, and/or mask, such element of headgear may be connected via wired, wireless, and/or network connection to remote device.

With continued reference to FIGS. 1-5 , in an illustrative example, detection of a physiological alarm condition may include determination, by the processor 120, that the user is losing consciousness. Alternatively or additionally, detection may include determination that user is about to lose consciousness. This may be achieved by comparing one or more physiological parameters and/or environmental parameters to a relationship, threshold, or baseline, which may be any relationship, threshold, or baseline as described above; for instance and without limitation, where blood oxygen level drops below a threshold percentage of a baseline level, below an absolute threshold amount, below a certain number of standard deviations, or the like, processor 120 may determine that user is about to lose consciousness or is losing consciousness, and issue an alarm. Alternatively or additionally, aggregation as described above may determine that imminent loss of consciousness is predicted by a particular set of values for one or more parameters as described above, processor 120 may detect a physiological alarm condition by detecting the particular set of values, indicating that user is about to lose consciousness. In an embodiment, determination of user state and/or physiological alarm condition may filter out anomalous or transient readings, or readings altered by motion of one or more elements of user's body or environment; for instance, determination may include determination of a particular parameter value for longer than a predetermined amount of time.

As another example, and still viewing FIGS. 1-5 , detection of the physiological alarm condition further comprises determination that the user is falling asleep; this may occur, for instance, where a neural activity sensor detects that a user is entering into an early stage of sleep, or “dozing off,” for instance by detection of a change in brainwaves. In an embodiment, processor 120 may generate an alarm where alpha wave activity drops by a threshold percentage, by a threshold amount, or the like; alternatively or additionally, one or more sets of brainwave patterns determined by processor 120 to be associated with user falling asleep, for instance by aggregation or machine-learning methods as described above, may be detected by processor 120 via at least a neural activity sensor, triggering an alarm. This may, as a non-limiting example, aid in preventing a commercial pilot who is not actively operating flight controls from partially or wholly falling asleep, which is a particular concern on long flights.

With continued reference to FIGS. 1-5 , detection of a physiological alarm condition may further include detection of at least an environmental parameter, and detection of physiological alarm condition as a function of the at least an environmental parameter. For instance, aggregation and/or machine learning processes as described above may determine that a reduction in cranial blood pressure coupled with an increase in acceleration indicates a probable loss of consciousness in a user; an alarm may therefore be triggered by detection, by processor 120, of that combination of decreased cranial blood pressure and increased acceleration.

Still viewing FIGS. 1-5 , processor 120 may incorporate or be in communication with at least a user-signaling device 128. In an embodiment, at least a user-signaling device 128 may be incorporated in device 100; for instance, at least a user-signaling device 128 may be attached to or incorporated in housing 104. Where at least a user-signaling device 128 contacts an exterior body surface of user, housing 104 may act to place at least a user-signaling device 128 in contact exterior body surface of user. Alternatively or additionally, device 100 may communicate with a user-signaling device 128 that is not incorporated in device 100, such as a display, headset, or other device provided by a third party or the like, which may be in communication with processor 120. User-signaling device 128 may be or incorporate a device for communication with an additional user-signaling device such as a vehicle display and/or helmet avionics; for instance, user-signaling device 128 may include a wireless transmitter or transponder in communication with such additional devices. In an embodiment, and without limitation, user-signaling device 128 may be configured to indicate the degree of pilot hypoxemia to at least a user, as described in further detail below.

Continuing to refer to FIGS. 1-5 , at least a user-signaling device 128 may include any device capable of transmitting an audible, tactile or visual signal to a user when triggered to do so by processor 120. In an embodiment, and as a non-limiting example, at least a user-signaling device 128 may include a bone-conducting transducer in vibrational contact with a bone beneath the exterior body surface. A bone-conducting transducer, as used herein, is a device or component that converts an electric signal to a vibrational signal that travels through bone placed in contact with the device or component to an inner ear of user, which interprets the vibration as an audible signal. Bone-conducting transducer may include, for instance, a piezoelectric element, which may be similar to the piezoelectric element found in speakers or headphones, which converts an electric signal into vibrations. In an embodiment, bone-conducting transducer may be mounted to housing 104 in a position placing it in contact with a user's bone; for instance, where housing 104 includes or is incorporated in an ear cup, housing 104 may place bone-conducting transducer in contact with user's skull just behind the ear, over the sternocleidomastoid muscle. Likewise, where housing 104 includes a headset, mask, or helmet, housing 104 may place bone-conducting transducer in contact with a portion of user's skull that is adjacent to or covered by headset, mask, or helmet.

Still referring to FIGS. 1-5 , at least a user-signaling device 128 may further include an audio output device. Audio output device may include any device that converts an electrical signal into an audible signal, including without limitation speakers, headsets, headphones, or the like. As a non-limiting example, audio output device may include a headset speaker of a headset incorporating or connected to device 100, a speaker in a vehicle user is traveling in, or the like. At least a user-signaling device 128 may include a light output device, which may be any device that converts an electrical signal into visible light; light output device may include one or more light source 604 s such as LEDs, as well as a display, which may be any display as described below in reference to FIG. 11 . At least a user-signaling device 128 may include a vehicular display; at least a vehicular display may be any display or combination of displays presenting information to a user of a vehicle user is operating. For instance, at least a vehicular display may include any combination of audio output devices, light output devices, display screens, and the like in an aircraft flight console, a car dashboard, a boat dashboard or console, or the like; processor 120 may be in communication with vehicular display using any form of communicative coupling described above, including without limitation wired or wireless connection. At least a user-signaling device 128 may include a helmet display; helmet display may include any visual, audio, or tactile display incorporated in any kind of helmet or headgear, which may be in communication with processor 120 according to any form of communicative coupling as described above.

Still viewing FIGS. 1-5 , user-signaling device 128 and/or processor 120 may be programmed to produce a variety of indications, which may correspond to various physiological alarm conditions and/or contexts. Possible indications may be, but are not limited to imminent unconsciousness, substandard oxygenation, erratic pulse, optimum oxygenation, and/or any other suitable indication, while maintaining the spirit of the present invention. Each such indication may have a distinct pattern of audible, visual, and/or textual indications; each indication may include, for instance, an audible or textual warning or description of a physiological alarm condition. Any of the above user-signaling devices 128 and/or signals may be used singly or in combination; for instance, a signal to user may include an audio signal produced using a bone-conducting transducer, a verbal warning message output by an audio output device, and a visual display of an image or text indicating the physiological alarm condition. Persons skilled in the art, upon reviewing the entirety of this disclosure, will be aware of various combinations of signaling means and/or processes that may be employed to convey a signal to user. In an embodiment, in addition to transmitting an alarm to user-signaling device 128, alert circuit may transmit a signal to one or more automated vehicular controls or other systems to alleviate one or more environmental parameters contributing to physiological alarm condition. For instance, and without limitation, an automated aircraft control may receive an indication of hypoxia while a motion sensor indicates high acceleration; aircraft control may reduce acceleration to alleviate the hypoxia. Persons skilled in the art, upon reviewing the entirety of this disclosure, may be aware of various additional ways in which automated systems may act to alleviate a physiological alarm condition as described herein.

Referring now to FIG. 8 , an embodiment of a system 800, which may incorporate an embodiment of device 100, as illustrated. Device 100 and/or any component thereof may be incorporated in system 800. Device 100 may be any device as disclosed above; system includes a processor 804, which may include any processor 120 as described above in reference to FIGS. 1-7 . Processor 804 is in communication with at least a physiological sensor 116, which may include any physiological sensor as described above in reference to FIGS. 1-7 . System 800 may include and/or communicate with a user signaling device 128, which may include any user signaling device 128 as described above in reference to FIGS. 1-8 . System 800 may include a memory 808, which may be a solid-state memory or the like; memory 808 may be used to record data during test periods, sorties, simulations, and the like, for instance as described above in reference to FIGS. 1-7 . System 800 may include a power source 812, which may include without limitation a local power storage device such as a battery or fuel cell.

Still viewing FIG. 8 , system 800 may communicate at times with an external device 816; communication may be continuous or episodic. For instance, and as described above in reference to FIGS. 1-8 , device 100 may communicate with external device 816 at the end of a session using an item of equipment, such as a sortie in an aircraft, a work day and/or work period, a dive, a shift, or the like; alternatively or additionally, device 100 may communicate continuously with external device 816 during at least a portion such as session, for instance to provide information to a person coordinating activities, such as a commanding officer, supervisor, manager, foreman, or the like. External device 816 may alternatively or additionally include a device incorporated in a simulation environment, vehicle, aircraft, item of equipment, or the like. System 800 may include or communicate with an external display 820. For instance, and without limitation external device 816 may provide information to an external display 820 including a monitor, audio communication device, or the like to a commanding officer, person recording a simulation, or the like. External display 820 may include a vehicular display as described above; vehicular display may receive information from user signaling device 128 and/or other components of device 100 to provide information to user and/or pilot. Data may be relayed from external device 816 to further memory devices and/or systems such as without limitation cloud storage 824; data may be analyzed in combination with additional data captured from pilot or other user, for instance during other sorties, simulations, or test periods, from additional users, or the like, and may be analyzed as described above to detect relationships between data detected by physiological sensors and/or environmental sensors as described above. Any relationship between any element of data captured by one or more physiological sensors, any element of data captured by one or more environmental sensors, and/or any element of data concerning a flight circumstance as described in further detail below, may be analyzed, calculated, and/or determined using machine learning and/or data analysis as described above.

Still referring to FIG. 8 , system may be installed in, and/or system 800 may include an item of equipment 828. Item of equipment may include, without limitation, a vehicle, such as an aircraft, watercraft, submarine, terrestrial vehicle such as a truck, tank, armored vehicle, fire engine, a specialized machine such as a drill, a portable or stationary crane, an excavator, or the like, and/or a wearable and/or on-person life-support item such as an apparatus for SCBA, SCUBA, a Reduced Oxygen Breathing Device (ROBD), a centrifuge or other device that varies G forces experienced by a user, a flight simulator, and/or an aircraft, including an aircraft the user and/or pilot is being trained to use.

Referring again to FIG. 1 , in some embodiments, system 100 may include a transducer (e.g., bone conducting transducer 128 or loudspeaker) configured to send an alarm signal to user. In some cases, processor may be further configured to generate alarm signal as a function of comparison between oxygenation signal and known human performance data. In some versions, alarm signal is an audible signal and transducer is a loudspeaker. Loudspeaker may include any speaker housed within housing 104 and configured to generate an audible signal which is perceptible to a user (e.g., wearer).

With continued reference to FIG. 1 , in some embodiments, system 100 may include a commercial aviation headset. For instance housing 104, outer shell 108 and seal 112 may be constituent parts of a commercial aviation headset. An exemplary commercial aviation headset is the Bose® A20 from Bose® Corporation of Framingham, Mass. Alternatively or additionally, in some embodiments, system 100 may be configured to be used with a commercial aviation headset. For instance, in some cases, system 100 may include a module which can interface with a commercial aviation headset. In some cases, system 100 may include an interface configured to communicate between processor and commercial aviation headset electronics. Interface may include any interface described in this disclosure, including with reference to FIG. 10 (e.g., network interface 1040 and/or peripheral interface 1056). Interface may include one or more of a wired connection and a wireless connection. Interface may be further configured to send an alarm signal to commercial headset to be communicated to user (e.g., wearer of commercial headset). As described throughout, processor may be configured to generate alarm signal as a function of comparison between an oxygenation signal and known human performance data. In some cases, alarm signal may include or be representative of an audible signal.

Referring now to FIG. 9 , an exemplary embodiment of a method 900 of detecting unsafe equipment operation conditions using physiological sensors is illustrated. At step 905, a processor in communication with a plurality of wearable physiological sensors detects at least a physiological parameter of an operator of an item of equipment. Physiological sensors may include any physiological sensors as described above, where physiological sensors are configured to be worn upon the person of a user, including without limitation mounting on or in clothing or gear worn for purposes of operating an item of equipment as set forth in further detail below. For instance, and without limitation, at least a physiological sensor may include a heart-rate sensor, a blood oxygen sensor, a sensor configured to detect neural oscillations, and/or a VOC sensor.

At step 910, and still referring to FIG. 9 , processor determines an equipment operation parametric model, wherein the equipment operation parametric rule relates physiological parameter sets to equipment operation requirements. Determining an equipment operation parametric model may include identifying, selecting, retrieving from program memory piecemeal or in its entirety, any equipment operation parametric model; an “equipment operation parametric model,” as used herein, is any stored relationship between combination of physiological and/or environmental parameters, including without limitation physiological and/or environmental parameters as described above, and one or more violations of an equipment operation requirements. An “equipment operation requirement,” as used in this disclosure, is a requirement regarding the physiological state of an operator that must be met for safe and/or effective operation of item of equipment 828. Such a requirement may be selected based on a degree of likelihood that an operator will suffer a physiological state violating the requirement. For instance, and without limitation, a pilot of a military aircraft is likely to suffer from oxygen deprivation and/or hypoxemia during a flight and/or sortie; oxygen deprivation and/or hypoxemia greater than a certain degree may be incompatible with safe operation of an aircraft, and may cause the pilot to crash the plane if left uncorrected. As a further example, an operator of a piece of industrial machinery and/or equipment may be at some risk, depending on conditions, to suffer hypothermia, heat stroke, sun stroke, dehydration, and/or stress-related effects, which may impair such an operator to the point where continued use of item of equipment would be unsafe for operator, equipment, or other persons. As an additional example, a diver, such as a commercial diver, and/or a member of a specialized construction profession such as a sand hog may be at risk to suffer oxygen deprivation, oxygen toxicity, carbon dioxide toxicity, nitrogen toxicity/intoxication, various neurological symptoms, panic, and/or decompression sickness, any of which in excess could lead to loss of life, failure to operate breathing apparatuses, lost or damaged equipment, or the like. A violation of equipment operation requirement may include any detected physiological state in which the user is unable to meet a requirement and/or threshold consistent with minimally safe and/or effective equipment operation.

Still referring to FIG. 9 , equipment operation parametric model may include any threshold and/or set of thresholds for any physiological parameter, as described above; such thresholds and/or sets of thresholds may be selected, without limitation, as described above, including entry by experts and/or operators, as set according to statistical measures of user performance for all users, demographic groups of users, and/or for a current user from whom plurality of physiological parameters is being measured in any embodiment of method 900. For instance, and without limitation, system 800 and/or processor 804 may determines a degree of pilot hypoxemia based on physiological parameter. For instance, where measuring includes measuring at least a hematological parameter determining may include determining the at least a hematological parameter is associated with the level of hypoxemia; this may be accomplished, without limitation, as described above. For instance, where measuring includes measuring a blood oxygen level, determining may include determining that the detected blood oxygen level is associated with the level of hypoxemia. This may be performed according to thresholds indicating levels of probable degrees of impairment associated with various percentages of blood oxygen saturation as described above; thresholds may include default thresholds set by factory or according to typical users, and/or thresholds set according to user values, for instance using changes to default thresholds as directed by data collected concerning user. As a further non-limiting example, where the at least a hematological parameter includes a heart rate, determining may include determining that the detected heart rate is associated with a level of hypoxemia; for instance and without limitation, an increase in heart rate, a change in blood pressure, or the like may indicate a likely movement from one threshold to another regarding blood oxygen saturation levels. Where measuring includes measuring a heart rate and a blood oxygen level, which may be a blood oxygen saturation level, determination may include determining that a combination of blood oxygen level and heart rate is associated with the level of hypoxemia; this may be performed as described above in reference to FIGS. 1-7 .

Still referring to FIG. 9 , a degree of hypoxemia may include a non-impairing degree of hypoxemia as described above; for instance, degree of hypoxemia may meet a threshold for a “possible problem,” which may also serve as an indication that blood oxygen condition of a pilot may be likely to deteriorate further. Degree of hypoxemia may include an impairing degree of hypoxemia; an impairing degree of hypoxemia may, for instance, relate to a second threshold as described above, for “performance degraded.” Degree of hypoxemia may include a degree of hypoxemia associated with an imminent loss of consciousness. Degree of hypoxemia may be determined by relationships between detected factors and/or physiological parameters. For instance, and without limitation, a decrease in blood oxygen saturation of 5% by itself may not suffice to trip a threshold based on blood oxygen saturation alone, but a concomitant increase in heart rate or decrease in blood pressure may cause processor 804 to determine that pilot has arrived at a higher or more severe degree of hypoxemia. As a further non-limiting example, one or more factors detected using at least a physiological sensor 116 and/or at least an environmental sensor 124 may cause processor 804 to treat a given hematological or other parameter as indicating a more or less severe degree of hypoxemia; such factors may include, without limitation, (1) detection of a degree of hydration of the pilot, where a lower degree of hydration may be associated with more acute hypoxemia for a given blood oxygen saturation level and/or heart rate; (2) a degree of pilot fatigue as determined, for instance, by brain wave activity, history or length of recent activity, or the like, and where a higher degree of fatigue or greater amount of recent flight activity may be associated with a more severe level of hypoxemia for a given blood oxygen saturation percentage and/or heart rate; (3) detected changes in neural oscillations, where, for instance, change indicating a tendency toward drowsiness, and or indication of entry into early stages of sleep or the like, where greater drowsiness and/or incipient hypnagogic states may indicate a higher degree of hypoxemia for a given blood oxygen saturation level and/or heart rate; (4) detected changes in ketone or VOC emission by user, where greater ketone and/or VOC emission indicates a higher degree of fatigue, which may be used as described above, and/or a more severe degree of hypoxemia for a given blood oxygen saturation level and/or heart rate; and/or (5) temperature, where a temperature significantly higher or lower than room temperature may be associated with a more severe degree of hypoxemia for a given blood oxygen saturation percentage and/or heart rate. Each such factor, or any combination thereof, may also be associated by processor 804 with a greater or lesser projected rate of degradation of pilot's degree of hypoxemia; for instance, a more fatigued pilot, or less hydrated pilot, may be more likely to descend from a current level of hypoxemia to a worse level than a well-rested or adequately hydrated pilot. A cumulative fatigue model may be generated or applied to determine a degree to which pilot fatigue affects either a current level of hypoxemia or a likely future rate of degradation. Degree of hypoxemia may include a degree of generalized or systemic hypoxemia, and/or a degree of cerebral and/or cranial hypoxemia.

In an embodiment, and still referring to FIG. 9 , operation parametric model may include a machine-learning model. Machine-learning model, and/or a machine-learning algorithm producing machine-learning model, may be trained and/or iteratively refined using training data. Training data, as used herein, is data containing correlations that a machine-learning process may use to model relationships between two or more categories of data elements. For instance, and without limitation, training data may include a plurality of data entries, each entry representing a set of data elements that were recorded, received, and/or generated together; data elements may be correlated by shared existence in a given data entry, by proximity in a given data entry, or the like. Multiple data entries in training data may evince one or more trends in correlations between categories of data elements; for instance, and without limitation, a higher value of a first data element belonging to a first category of data element may tend to correlate to a higher value of a second data element belonging to a second category of data element, indicating a possible proportional or other mathematical relationship linking values belonging to the two categories. Multiple categories of data elements may be related in training data according to various correlations; correlations may indicate causative and/or predictive links between categories of data elements, which may be modeled as relationships such as mathematical relationships by machine-learning processes as described in further detail below. Training data may be formatted and/or organized by categories of data elements, for instance by associating data elements with one or more descriptors corresponding to categories of data elements. As a non-limiting example, training data may include data entered in standardized forms by persons or processes, such that entry of a given data element in a given field in a form may be mapped to one or more descriptors of categories. Elements in training data may be linked to descriptors of categories by tags, tokens, or other data elements; for instance, and without limitation, training data may be provided in fixed-length formats, formats linking positions of data to categories such as comma-separated value (CSV) formats and/or self-describing formats such as extensible markup language (XML), enabling processes or devices to detect categories of data.

Alternatively or additionally, and still referring to FIG. 9 . training data may include one or more elements that are not categorized; that is, training data may not be formatted or contain descriptors for some elements of data. Machine-learning algorithms and/or other processes may sort training data according to one or more categorizations using, for instance, natural language processing algorithms, tokenization, detection of correlated values in raw data and the like; categories may be generated using correlation and/or other processing algorithms. As a non-limiting example, in a corpus of text, phrases making up a number “n” of compound words, such as nouns modified by other nouns, may be identified according to a statistically significant prevalence of n-grams containing such words in a particular order; such an n-gram may be categorized as an element of language such as a “word” to be tracked similarly to single words, generating a new category as a result of statistical analysis. Similarly, in a data entry including some textual data, a person's name may be identified by reference to a list, dictionary, or other compendium of terms, permitting ad-hoc categorization by machine-learning algorithms, and/or automated association of data in the data entry with descriptors or into a given format. The ability to categorize data entries automatedly may enable the same training data to be made applicable for two or more distinct machine-learning algorithms as described in further detail below. Training data used by process or may correlate any input data as described in this disclosure to any output data as described in this disclosure. As a non-limiting illustrative example training data may include training data sets correlating sets of physiological and/or environmental parameters to violation of an equipment operation requirement and/or data to be compared to thresholds to test for violations of equipment operation requirements.

With continued reference to FIG. 9 , processor, and/or a remote device in communication with processor, may be designed and configured to create a machine-learning model using techniques for development of linear regression models. Linear regression models may include ordinary least squares regression, which aims to minimize the square of the difference between predicted outcomes and actual outcomes according to an appropriate norm for measuring such a difference (e.g. a vector-space distance norm); coefficients of the resulting linear equation may be modified to improve minimization. Linear regression models may include ridge regression methods, where the function to be minimized includes the least-squares function plus term multiplying the square of each coefficient by a scalar amount to penalize large coefficients. Linear regression models may include least absolute shrinkage and selection operator (LASSO) models, in which ridge regression is combined with multiplying the least-squares term by a factor of 1 divided by double the number of samples. Linear regression models may include a multi-task lasso model wherein the norm applied in the least-squares term of the lasso model is the Frobenius norm amounting to the square root of the sum of squares of all terms. Linear regression models may include the elastic net model, a multi-task elastic net model, a least angle regression model, a LARS lasso model, an orthogonal matching pursuit model, a Bayesian regression model, a logistic regression model, a stochastic gradient descent model, a perceptron model, a passive aggressive algorithm, a robustness regression model, a Huber regression model, or any other suitable model that may occur to persons skilled in the art upon reviewing the entirety of this disclosure. Linear regression models may be generalized in an embodiment to polynomial regression models, whereby a polynomial equation (e.g. a quadratic, cubic or higher-order equation) providing a best predicted output/actual output fit is sought; similar methods to those described above may be applied to minimize error functions, as will be apparent to persons skilled in the art upon reviewing the entirety of this disclosure.

Continuing to refer to FIG. 9 , machine-learning algorithms may include, without limitation, linear discriminant analysis. Machine-learning algorithm may include quadratic discriminate analysis. Machine-learning algorithms may include kernel ridge regression. Machine-learning algorithms may include support vector machines, including without limitation support vector classification-based regression processes. Machine-learning algorithms may include stochastic gradient descent algorithms, including classification and regression algorithms based on stochastic gradient descent. Machine-learning algorithms may include nearest neighbors algorithms. Machine-learning algorithms may include Gaussian processes such as Gaussian Process Regression. Machine-learning algorithms may include cross-decomposition algorithms, including partial least squares and/or canonical correlation analysis. Machine-learning algorithms may include naïve Bayes methods. Machine-learning algorithms may include algorithms based on decision trees, such as decision tree classification or regression algorithms. Machine-learning algorithms may include ensemble methods such as bagging meta-estimator, forest of randomized tress, AdaBoost, gradient tree boosting, and/or voting classifier methods. Machine-learning algorithms may include neural net algorithms, including convolutional neural net processes.

Still referring to FIG. 9 , models may be generated using alternative or additional artificial intelligence methods, including without limitation by creating an artificial neural network, such as a convolutional neural network comprising an input layer of nodes, one or more intermediate layers, and an output layer of nodes. Connections between nodes may be created via the process of “training” the network, in which elements from a training dataset are applied to the input nodes, a suitable training algorithm (such as Levenberg-Marquardt, conjugate gradient, simulated annealing, or other algorithms) is then used to adjust the connections and weights between nodes in adjacent layers of the neural network to produce the desired values at the output nodes. This process is sometimes referred to as deep learning. This network may be trained using training data.

Further referring to FIG. 9 , machine-learning algorithms may include supervised machine-learning algorithms. Supervised machine learning algorithms, as defined herein, include algorithms that receive a training set relating a number of inputs to a number of outputs, and seek to find one or more mathematical relations relating inputs to outputs, where each of the one or more mathematical relations is optimal according to some criterion specified to the algorithm using some scoring function. For instance, a supervised learning algorithm may include combinations of physiological parameters and/or environmental parameters as described above as inputs, violations of equipment operation requirements, and/or data comparable to thresholds for detection thereof, as outputs, and a scoring function representing a desired form of relationship to be detected between inputs and outputs; scoring function may, for instance, seek to maximize the probability that a given input and/or combination of elements inputs is associated with a given output to minimize the probability that a given input is not associated with a given output. Scoring function may be expressed as a risk function representing an “expected loss” of an algorithm relating inputs to outputs, where loss is computed as an error function representing a degree to which a prediction generated by the relation is incorrect when compared to a given input-output pair provided in training data. Persons skilled in the art, upon reviewing the entirety of this disclosure, will be aware of various possible variations of supervised machine learning algorithms that may be used to determine relation between inputs and outputs.

Still referring to FIG. 9 , supervised machine-learning processes may include classification algorithms as described in further detail below and defined as processes whereby a computing device derives, from training data, a model for sorting inputs into categories or bins of data. Classification may be performed using, without limitation, linear classifiers such as without limitation logistic regression and/or naive Bayes classifiers, nearest neighbor classifiers, support vector machines, decision trees, boosted trees, random forest classifiers, and/or neural network-based classifiers.

With continued reference to FIG. 9 , machine learning processes may include unsupervised processes. An unsupervised machine-learning process, as used herein, is a process that derives inferences in datasets without regard to labels; as a result, an unsupervised machine-learning process may be free to discover any structure, relationship, and/or correlation provided in the data. Unsupervised processes may not require a response variable; unsupervised processes may be used to find interesting patterns and/or inferences between variables, to determine a degree of correlation between two or more variables, or the like.

Still referring to FIG. 9 , machine-learning processes as described in this disclosure may be used to generate machine-learning models. A machine-learning model, as used herein, is a mathematical representation of a relationship between inputs and outputs, as generated using any machine-learning process including without limitation any process as described above, and stored in memory; an input is submitted to a machine-learning model once created, which generates an output based on the relationship that was derived. For instance, and without limitation, a linear regression model, generated using a linear regression algorithm, may compute a linear combination of input data using coefficients derived during machine-learning processes to calculate an output datum. As a further non-limiting example, a machine-learning model may be generated by creating an artificial neural network, such as a convolutional neural network comprising an input layer of nodes, one or more intermediate layers, and an output layer of nodes. Connections between nodes may be created via the process of “training” the network, in which elements from a training dataset are applied to the input nodes, a suitable training algorithm (such as Levenberg-Marquardt, conjugate gradient, simulated annealing, or other algorithms) is then used to adjust the connections and weights between nodes in adjacent layers of the neural network to produce the desired values at the output nodes. This process is sometimes referred to as deep learning.

With continued reference to FIG. 9 , machine-learning model may further include a user-specific model; user specific model may include any machine-learning model, as described in this disclosure, that is developed using training data specific to a user, such as any user-specific data described above aggregated to develop user-specific baselines or the like. A user-specific model may be trained solely using such user-specific training data; alternatively or additionally, processor and/or a remote device may generate a machine-learning model based on data collected for a plurality of persons, such as persons matching a one or more demographic category and/or grouping to which user belongs, and processor and/or a remote device may subsequently train such a model with user-specific training data.

Still referring to FIG. 9 , processor may determine equipment operation parametric model by retrieval from program memory and/or circuitry of processor; there may be only one equipment operation parametric model in program memory, which may be loaded prior to and/or during operation from additional memory and/or a remote device according to any selection and/or retrieval process described below. Alternatively or additionally, processor may select equipment operation parametric model from two or more equipment operation parametric models stored in program and/or other memory. Selection may include receiving an identifier of item of equipment 828, user, and/or one or more contextual data describing circumstances of equipment operation.

As a non-limiting example, system 800 deployed in an aircraft may select an equipment operation parametric model for an aircraft based on a flight condition. A flight condition, as used herein, is any set of circumstances in an aircraft, flight simulator, or other item of equipment 828; at least a flight condition may include any state of environment or modification to environment within an item of equipment 828 that item of equipment 828 is commanded by a person or system to perform, including a change in air pressure, oxygen content, acceleration, direction, rotational or angular velocity, barometric pressure, variations in temperature, or the like. At least a flight condition may include any condition detectable using at least an environmental sensor 124. At least a flight condition having a causative association with hypoxemia may include any circumstance in a flight and/or flight simulation tending to cause either generalized or cranial/cerebral hypoxemia, including without limitation high G-forces imposed by acceleration of an aircraft, motion of a centrifuge, or the like, low atmospheric and/or respirator oxygen contents, low barometric pressure, and the like. Data analysis and/or machine learning as described above may be used to detect relationships between flight conditions and hypoxemia.

Alternatively or additionally, and continuing to refer to FIG. 9 , determining equipment operation parametric model may include performing a classification process to determine the equipment operation parametric model. A “classifier,” as used in this disclosure is a machine-learning model, such as a mathematical model, neural net, or program generated by a machine learning algorithm known as a “classification algorithm” and/or “classification process” as described in further detail below, that sorts inputs into categories or bins of data, outputting the categories or bins of data and/or labels associated therewith. A classifier may be configured to output at least a datum that labels or otherwise identifies a set of data that are clustered together, found to be close under a distance metric as described below, or the like. Computing device 104 and/or another device may generate a classifier using a classification algorithm, defined as a processes whereby a computing device 104 derives a classifier from training data. Classification may be performed using, without limitation, linear classifiers such as without limitation logistic regression and/or naive Bayes classifiers, nearest neighbor classifiers such as k-nearest neighbors classifiers, support vector machines, least squares support vector machines, fisher's linear discriminant, quadratic classifiers, decision trees, boosted trees, random forest classifiers, learning vector quantization, and/or neural network-based classifiers.

Still referring to FIG. 9 , processor and/or a remote device may be configured to generate a classifier using a Naïve Bayes classification algorithm. Naïve Bayes classification algorithm generates classifiers by assigning class labels to problem instances, represented as vectors of element values. Class labels are drawn from a finite set. Naïve Bayes classification algorithm may include generating a family of algorithms that assume that the value of a particular element is independent of the value of any other element, given a class variable. Naïve Bayes classification algorithm may be based on Bayes Theorem expressed as P(A/B)=P(B/A) P(A)±P(B), where P(AB) is the probability of hypothesis A given data B also known as posterior probability; P(B/A) is the probability of data B given that the hypothesis A was true; P(A) is the probability of hypothesis A being true regardless of data also known as prior probability of A; and P(B) is the probability of the data regardless of the hypothesis. A naïve Bayes algorithm may be generated by first transforming training data into a frequency table. Computing device 104 may then calculate a likelihood table by calculating probabilities of different data entries and classification labels. Computing device 104 may utilize a naïve Bayes equation to calculate a posterior probability for each class. A class containing the highest posterior probability is the outcome of prediction. Naïve Bayes classification algorithm may include a gaussian model that follows a normal distribution. Naïve Bayes classification algorithm may include a multinomial model that is used for discrete counts. Naïve Bayes classification algorithm may include a Bernoulli model that may be utilized when vectors are binary.

With continued reference to FIG. 9 , processor and/or a remote device may be configured to generate a classifier using a K-nearest neighbors (KNN) algorithm. A “K-nearest neighbors algorithm” as used in this disclosure, includes a classification method that utilizes feature similarity to analyze how closely out-of-sample-features resemble training data to classify input data to one or more clusters and/or categories of features as represented in training data; this may be performed by representing both training data and input data in vector forms, and using one or more measures of vector similarity to identify classifications within training data, and to determine a classification of input data. K-nearest neighbors algorithm may include specifying a K-value, or a number directing the classifier to select the k most similar entries training data to a given sample, determining the most common classifier of the entries in the database, and classifying the known sample; this may be performed recursively and/or iteratively to generate a classifier that may be used to classify input data as further samples. For instance, an initial set of samples may be performed to cover an initial heuristic and/or “first guess” at an output and/or relationship, which may be seeded, without limitation, using expert input received according to any process as described herein. As a non-limiting example, an initial heuristic may include a ranking of associations between inputs and elements of training data. Heuristic may include selecting some number of highest-ranking associations and/or training data elements.

Still referring to FIG. 9 , generating k-nearest neighbors algorithm may generate a first vector output containing a data entry cluster, generating a second vector output containing an input data, and calculate the distance between the first vector output and the second vector output using any suitable norm such as cosine similarity, Euclidean distance measurement, or the like. Each vector output may be represented, without limitation, as an n-tuple of values, where n is at least two values. Each value of n-tuple of values may represent a measurement or other quantitative value associated with a given category of data, or attribute, examples of which are provided in further detail below; a vector may be represented, without limitation, in n-dimensional space using an axis per category of value represented in n-tuple of values, such that a vector has a geometric direction characterizing the relative quantities of attributes in the n-tuple as compared to each other. Two vectors may be considered equivalent where their directions, and/or the relative quantities of values within each vector as compared to each other, are the same; thus, as a non-limiting example, a vector represented as [5, 10, 15] may be treated as equivalent, for purposes of this disclosure, as a vector represented as [1, 2, 3]. Vectors may be more similar where their directions are more similar, and more different where their directions are more divergent; however, vector similarity may alternatively or additionally be determined using averages of similarities between like attributes, or any other measure of similarity suitable for any n-tuple of values, or aggregation of numerical similarity measures for the purposes of loss functions as described in further detail below. Any vectors as described herein may be scaled, such that each vector represents each attribute along an equivalent scale of values. Each vector may be “normalized,” or divided by a “length” attribute, such as a length attribute l as derived using a Pythagorean norm: l=√{square root over (Σ_(i=0) ^(n)a_(i) ²)}, where a_(i) is attribute number i of the vector. Scaling and/or normalization may function to make vector comparison independent of absolute quantities of attributes, while preserving any dependency on similarity of attributes; this may, for instance, be advantageous where cases represented in training data are represented by different quantities of samples, which may result in proportionally equivalent vectors with divergent values.

With continued reference to FIG. 9 , inputs to classification process may include an environmental parameter detected using an environmental sensor; inputs may include a plurality of environmental parameters. Environmental sensor may include any environmental sensors and/or combinations thereof as described above, including a motion sensor an atmospheric oxygen sensor, a pressure sensor, or the like.

Further referring to FIG. 9 , and as a non-limiting example, machine-learning model may include a classifier, as defined above, that inputs sets of physiological and/or environmental parameters and outputs violations and/or data that may be compared to a threshold and/or requirement. Alternatively or additionally, machine-learning algorithm may include a regression model that inputs sets of physiological and/or environmental parameters and outputs violations and/or data that may be compared to a threshold and/or requirement; output may include, for instance, a score calculated via an equation or other mathematical function of parameters having coefficients determined via a regression process, which may be compared to a threshold value. Any of machine-learning model, classifier, or the like may be generated by processor 804 and/or by a remote device 816; in the latter case, processor 804 may upload machine-learning model, classifier, or the like from remote device 816 in the form of software, memory files, firmware, or the like, either during or prior to use of item of equipment.

At step 915, and continuing to refer to FIG. 9 , processor detects, using the equipment operation parametric model and the plurality of physiological parameters, a violation of an equipment operation requirement. Detection may be performed using any form of threshold comparison and/or other comparison and/or detection method for any alert condition as described above, for instance where the alert condition describes and/or indicates a physiological condition and/or state that violates an equipment operation requirement. Detection may alternatively or additionally include inputting one or more physiological parameters, one or more environmental parameters, and/or any combination thereof to a machine-learning model, receiving an output from the machine-learning model identifying a violation, and detecting the violation based on the output, including without limitation comparing a quantitative output to a threshold, for instance by comparing an output indicative of a probability of suffering a degraded ability to an upper threshold, an output indicative of a probability of successful performance of an important and/or critical function to a lower threshold indictive of inability to perform adequately, or the like.

At step 920, and with continued reference to FIG. 9 , processor generates a violation response action in response to detecting the violation; this may be performed according to any process and/or processes described above for generation and/or output of alerts. Violation response action may further include, without limitation stopping, pausing, and/or shutting off item of equipment 828 to prevent an accident, injury, damage to equipment, or other negative outcome. Violation response action may include transmitting a signal to another user and/or equipment item indicating that user and/or item of equipment 828 is in need of assistance, unable to perform, in need of rescue, or otherwise in need of intervention

Still referring to FIG. 9 , and as a non-limiting example, generation of a violation response action may include generation of at least a pilot-specific flight guideline, which may include determining an association between at least a physiological condition, at least a flight condition, and/or other information concerning pilot and/or other user. At least a pilot-specific flight guideline may be based on baseline data regarding pilot, on one or more training or mission goals, or both. For instance, a goal of a training session may be for a pilot to operate under light (e.g., relating to a first threshold level as described above) to moderate (e.g., relating to a second threshold level as described above) hypoxemia, for a certain period of time intended, for instance, to indicate circumstances under which a mission-critical or otherwise important maneuver or act must be performed at high altitudes, high speeds, or other circumstances likely to induce at least a degree of hypoxemia; length of period and/or degree of hypoxemia experienced may be set according to pilot's record of past performance, baselines recorded regarding that pilot's performance under light to moderate hypoxemia and/or that pilot's tendency to degrade to higher degrees of hypoxemia under some circumstances, or the like. Another goal may, for instance be to have pilot undergo a particular environmental condition, such as atmospheric oxygen below a set level and/or a series of high-G maneuvers and/or periods, and to attempt and/or practice strategies for avoiding incapacitation. A second instruction may issue, as well; for instance, if pilot is degrading more than expected, a training session may be modified to be less severe or aborted. At least a pilot-specific flight guideline may be provided to at least a user and/or a flight condition generation device 828 as an instruction, as described above. As noted above, any data regarding past pilot performance, baselines, and the like, together with correlated physiological parameters, environmental parameters, and/or flight conditions as described above may be analyzed using data analysis and/or machine learning as described above, to derive mathematical relationships between various factors; such relationships can be used to set thresholds, for instance as described above, and to plan pilot training and/or missions to remain within certain threshold ranges, to increase pilot resistance to hypoxemia and extend such threshold ranges, or the like. In an embodiment, both device 100 and pilot may learn in each mission and/or training session to work more effectively within the physiological limits of the pilot, enabling a greater range of actions to be performed to a higher degree of safety. Methods as described herein and/or device 100 may enable training profiles to identify potential shortfalls and/or difficulties, for instance by modifying training profiles and/or plans to avoid detected episodes of hypoxemia, either for particular pilots 812, for particular cohorts or demographic sets of pilots, or for pilots in general.

As a further example, a violation response action may direct a device, such as an ROBD or the like, that adjusts physical conditions of a user, such as atmospheric oxygen levels and/or barometric pressure experienced by a pilot, to adjust such a physical condition, such as without limitation oxygen level and/or barometric pressure; such a command may be transmitted and/or otherwise provided to training and processor 804 as a flight condition. As a further example, where item of equipment 828 is a device that varies G forces on a user, such as a centrifuge, item of equipment 828 may receive or automatically generate a command to increase and/or decrease G forces on user, such as a command to increase and/or decrease angular velocity of a centrifuge; this command may be transmitted or otherwise provided to processor 804 as a flight condition. Where item of equipment 828, one or more commands from user, system 800, autopilot guidance computer or instrumentation, or the like may be provided to processor 804; for instance, pilot manual controls in a fly-by-wire or partial fly-by-wire aircraft may take the form of electronic signals, which may also be transmitted and/or provided to processor 804. Flight plan or precalculated trajectory data may be provided to processor 804 as part of data describing at least a flight condition; for instance, a fly-by-wire system may be programmed to respond to a particular pilot and/or autopilot command by causing an aircraft to traverse a certain trajectory at a certain velocity or with a certain acceleration.

It is to be noted that any one or more of the aspects and embodiments described herein may be conveniently implemented using one or more machines (e.g., one or more computing devices that are utilized as a user computing device for an electronic document, one or more server devices, such as a document server, etc.) programmed according to the teachings of the present specification, as will be apparent to those of ordinary skill in the computer art. Appropriate software coding can readily be prepared by skilled programmers based on the teachings of the present disclosure, as will be apparent to those of ordinary skill in the software art. Aspects and implementations discussed above employing software and/or software modules may also include appropriate hardware for assisting in the implementation of the machine executable instructions of the software and/or software module.

Such software may be a computer program product that employs a machine-readable storage medium. A machine-readable storage medium may be any medium that is capable of storing and/or encoding a sequence of instructions for execution by a machine (e.g., a computing device) and that causes the machine to perform any one of the methodologies and/or embodiments described herein. Examples of a machine-readable storage medium include, but are not limited to, a magnetic disk, an optical disc (e.g., CD, CD-R, DVD, DVD-R, etc.), a magneto-optical disk, a read-only memory “ROM” device, a random-access memory “RAM” device, a magnetic card, an optical card, a solid-state memory device, an EPROM, an EEPROM, and any combinations thereof. A machine-readable medium, as used herein, is intended to include a single medium as well as a collection of physically separate media, such as, for example, a collection of compact discs or one or more hard disk drives in combination with a computer memory. As used herein, a machine-readable storage medium does not include transitory forms of signal transmission.

Such software may also include information (e.g., data) carried as a data signal on a data carrier, such as a carrier wave. For example, machine-executable information may be included as a data-carrying signal embodied in a data carrier in which the signal encodes a sequence of instruction, or portion thereof, for execution by a machine (e.g., a computing device) and any related information (e.g., data structures and data) that causes the machine to perform any one of the methodologies and/or embodiments described herein.

Examples of a computing device include, but are not limited to, an electronic book reading device, a computer workstation, a terminal computer, a server computer, a handheld device (e.g., a tablet computer, a smartphone, etc.), a web appliance, a network router, a network switch, a network bridge, any machine capable of executing a sequence of instructions that specify an action to be taken by that machine, and any combinations thereof. In one example, a computing device may include and/or be included in a kiosk.

FIG. 11 shows a diagrammatic representation of one embodiment of a computing device in the exemplary form of a computer system 1100 within which a set of instructions for causing a control system, such as the device 100 disclosed above, to perform any one or more of the aspects and/or methodologies of the present disclosure may be executed. It is also contemplated that multiple computing devices may be utilized to implement a specially configured set of instructions for causing one or more of the devices to perform any one or more of the aspects and/or methodologies of the present disclosure. Computer system 1100 includes a processor 1104 and a memory 1108 that communicate with each other, and with other components, via a bus 1112. Bus 1112 may include any of several types of bus structures including, but not limited to, a memory bus, a memory controller, a peripheral bus, a local bus, and any combinations thereof, using any of a variety of bus architectures.

Memory 1108 may include various components (e.g., machine-readable media) including, but not limited to, a random-access memory component, a read only component, and any combinations thereof. In one example, a basic input/output system 1116 (BIOS), including basic routines that help to transfer information between elements within computer system 1100, such as during start-up, may be stored in memory 1108. Memory 1108 may also include (e.g., stored on one or more machine-readable media) instructions (e.g., software) 1120 embodying any one or more of the aspects and/or methodologies of the present disclosure. In another example, memory 1108 may further include any number of program modules including, but not limited to, an operating system, one or more application programs, other program modules, program data, and any combinations thereof.

Computer system 1100 may also include a storage device 1124. Examples of a storage device (e.g., storage device 1124) include, but are not limited to, a hard disk drive, a magnetic disk drive, an optical disc drive in combination with an optical medium, a solid-state memory device, and any combinations thereof. Storage device 1124 may be connected to bus 1112 by an appropriate interface (not shown). Example interfaces include, but are not limited to, SCSI, advanced technology attachment (ATA), serial ATA, universal serial bus (USB), IEEE 1394 (FIREWIRE), and any combinations thereof. In one example, storage device 1124 (or one or more components thereof) may be removably interfaced with computer system 1100 (e.g., via an external port connector (not shown)). Particularly, storage device 1124 and an associated machine-readable medium 1128 may provide nonvolatile and/or volatile storage of machine-readable instructions, data structures, program modules, and/or other data for computer system 1100. In one example, software 1120 may reside, completely or partially, within machine-readable medium 1128. In another example, software 1120 may reside, completely or partially, within processor 1104.

Computer system 1100 may also include an input device 1132. In one example, a user of computer system 1100 may enter commands and/or other information into computer system 1100 via input device 1132. Examples of an input device 1132 include, but are not limited to, an alpha-numeric input device (e.g., a keyboard), a pointing device, a joystick, a gamepad, an audio input device (e.g., a microphone, a voice response system, etc.), a cursor control device (e.g., a mouse), a touchpad, an optical scanner, a video capture device (e.g., a still camera, a video camera), a touchscreen, and any combinations thereof. Input device 1132 may be interfaced to bus 1112 via any of a variety of interfaces (not shown) including, but not limited to, a serial interface, a parallel interface, a game port, a USB interface, a FIREWIRE interface, a direct interface to bus 1112, and any combinations thereof. Input device 1132 may include a touch screen interface that may be a part of or separate from display 1136, discussed further below. Input device 1132 may be utilized as a user selection device for selecting one or more graphical representations in a graphical interface as described above.

A user may also input commands and/or other information to computer system 1100 via storage device 1124 (e.g., a removable disk drive, a flash drive, etc.) and/or network interface device 1140. A network interface device, such as network interface device 1140, may be utilized for connecting computer system 1100 to one or more of a variety of networks, such as network 1144, and one or more remote devices 1148 connected thereto. Examples of a network interface device include, but are not limited to, a network interface card (e.g., a mobile network interface card, a LAN card), a modem, and any combination thereof. Examples of a network include, but are not limited to, a wide area network (e.g., the Internet, an enterprise network), a local area network (e.g., a network associated with an office, a building, a campus or other relatively small geographic space), a telephone network, a data network associated with a telephone/voice provider (e.g., a mobile communications provider data and/or voice network), a direct connection between two computing devices, and any combinations thereof. A network, such as network 1144, may employ a wired and/or a wireless mode of communication. In general, any network topology may be used. Information (e.g., data, software 1120, etc.) may be communicated to and/or from computer system 1100 via network interface device 1140.

Computer system 1100 may further include a video display adapter 1152 for communicating a displayable image to a display device, such as display device 1136. Examples of a display device include, but are not limited to, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, a light emitting diode (LED) display, and any combinations thereof. Display adapter 1152 and display device 1136 may be utilized in combination with processor 1104 to provide graphical representations of aspects of the present disclosure. In addition to a display device, computer system 1100 may include one or more other peripheral output devices including, but not limited to, an audio speaker, a printer, and any combinations thereof. Such peripheral output devices may be connected to bus 1112 via a peripheral interface 1156. Examples of a peripheral interface include, but are not limited to, a serial port, a USB connection, a FIREWIRE connection, a parallel connection, and any combinations thereof.

The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope of this invention. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present invention. Additionally, although particular methods herein may be illustrated and/or described as being performed in a specific order, the ordering is highly variable within ordinary skill to achieve methods, systems, devices and/or software according to the present disclosure. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.

Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention. 

What is claimed is:
 1. A system for measuring oxygenation signals, comprising: an outer shell; a seal coupled to the outer shell; a blood oxygen sensor configured to: be in contact with a user; be located behind an ear of the user; and measure an oxygenation signal of the user; a processor configured to: receive the oxygenation signal from the blood oxygen sensor; and compare the oxygenation signal from the blood oxygenation sensor with known human performance data.
 2. The system of claim 1, wherein the blood oxygen sensor is located proximal the user's sternocleidomastoid muscle.
 3. The system of claim 1, further comprising: a transducer configured to send an alarm signal to the user; and wherein the processor is further configured to generate the alarm signal as a function of the comparison between the oxygenation signal and the known human performance data.
 4. The system of claim 3, wherein the alarm signal is an audible signal.
 5. The system of claim 1, comprising a commercial aviation headset.
 6. The system of claim 1, wherein the system is configured to be used with a commercial aviation headset.
 7. The system of claim 6, further comprising: an interface configured to communicate between the processor and the commercial aviation headset electronics.
 8. The system of claim 7, wherein: the interface is further configured to send an alarm signal to the commercial headset to be communicated to the user; and the processor is further configured to generate the alarm signal as a function of the comparison between the oxygenation signal and the known human performance data.
 9. The system of claim 8, wherein the alarm signal is an audible signal.
 10. The system of claim 7 wherein the interface is one or more of a wired connection and a wireless connection.
 11. A method for measuring oxygenation signals, using a system comprising an outer shell, a seal coupled to the outer shell, a blood oxygen sensor, and a processor, wherein the method comprises: contacting a user, using the blood oxygen sensor; locating the blood oxygen sensor behind an ear of the user; measuring, using the blood oxygen sensor, an oxygenation signal of the user; receiving, using the processor, the oxygenation signal from the blood oxygen sensor; and comparing, using the processor, the oxygenation signal from the blood oxygenation sensor with known human performance data.
 12. The method of claim 11, wherein the blood oxygen sensor is located proximal the user's sternocleidomastoid muscle.
 13. The method of claim 11, further comprising: sending, using a transducer, an alarm signal to the user; and generating, using the processor, the alarm signal as a function of the comparison between the oxygenation signal and the known human performance data.
 14. The method of claim 13, wherein the alarm signal is an audible signal.
 15. The method of claim 11, wherein the system comprises a commercial aviation headset.
 16. The method of claim 11, wherein the system is configured to be used with a commercial aviation headset.
 17. The method of claim 16, further comprising: communicating, using an interface, between the processor and the commercial aviation headset electronics.
 18. The method of claim 17, wherein: sending, using the interface, an alarm signal to the commercial headset to be communicated to the user; and generating, using the processor, the alarm signal as a function of the comparison between the oxygenation signal and the known human performance data.
 19. The method of claim 18, wherein the alarm signal is an audible signal.
 20. The method of claim 17 wherein the interface is one or more of a wired connection and a wireless connection. 